<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>盒模型</title>
    <style>
        .simple {
            background: aqua;
            width: 500px;
            margin: 20px auto;
        }

        .fancy {
            background: antiquewhite;
            width: 500px;
            margin: 20px auto;
            padding: 50px;
            border-width: 10px;
        }
    </style>
</head>
<body>
    <div class="simple">我小一些...</div>
    <div class="fancy">我比他大！</div>
</body>
</html>